Leece-neville made an alt in the old days for semi's It had a square plug on it. Pull in out, turn 90* plug back in Do this in all 4 positions and everyone had a different output. Fron 60x to 110a. Not sure if they are still around but with some fab skills one could add this and have a dedicated charging systwm for the trailer. The Ford 7.3 & 6.0's have an anbulance pkg for 2 alt one for the vehicle and one for the coach. My tuuck came with the mount So I could add the other alt and just wire it to the trailer not not worth the expense or work IMO. I have survived 15 yrs without it but would be a nice setup.